Flow transitions and flow localization in large-strain deformation of magnesium alloy


Sagapuram D., EFE M., Trumble K. P. , Chandrasekar S.

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, vol.659, pp.295-305, 2016 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 659
  • Publication Date: 2016
  • Doi Number: 10.1016/j.msea.2016.02.054
  • Journal Name: MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.295-305

Abstract

Understanding transitions from homogeneous to localized flow, and mechanisms underlying flow localization, is of paramount importance for deformation processing of magnesium. In this study, a shear based deformation method is utilized for imposing large strains (similar to 1), under controllable strain rates (10-10(5)/s) and temperatures (80-300 degrees C), in order to examine flow patterns in a magnesium alloy. Based on microstructure characterization, deformation twinning is suggested to contribute to the localized flow at temperatures below 200 degrees C and at low strain rates. The transition from the localized to homogeneous flow with increasing temperature is due to reduction in twinning activity, and enhanced strain-rate sensitivity. At constant temperature, an increase in the strain rate decreases the propensity for flow localization. A model is presented for characterizing the maximum uniform strain as a function of temperature and deformation state (simple shear, plane-strain compression). The model incorporates temperature-sensitive microstructural changes and flow properties of magnesium into a classical framework to capture the flow localization phenomena at low temperatures and strain rates. (C) 2016 Elsevier B.V. All rights reserved.